During drilling operations, formation fluids and gases may become entrapped in drilling fluid. These gases may be extracted at the surface in a mechanical agitation gas trap and analyzed using a gas chromatographer, mass spectrometer, or like equipment to thereby determine a hydrocarbon profile of the formation per lineal foot drilled for the entire depth of the well. In particular, the molar concentrations of the vapor-phase various components of interest are measured by the gas chromatographer, mass spectrometer, or other analytical equipment, and equation of state calculations using this data are then utilized to extrapolate this measured data into a hydrocarbon profile.
Many different equations of state have been developed to describe the thermodynamic and chemical state of a system. The oil and gas industry traditionally uses the Peng-Robinson equation of state for mud logging purposes with moderate success. However, current mud logging techniques suffer from inaccuracies that require correction factors to be determined and applied. For instance, it is a known practice to initially circulate drilling fluid in a bucket while mud logging measurements and correlate the measurements with laboratory testing to determine correction factors prior to drilling. These methods are not practiced in real time due to the need to obtain periodic experimental laboratory testing to obtain accurate results.